diff --git a/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc b/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
index 5daa7eb8ded..9991e4b14f3 100644
--- a/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
+++ b/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
@@ -24,20 +24,6 @@
 namespace Rust {
 namespace HIR {
 
-void
-mkdir_wrapped (const std::string &dirname)
-{
-  int ret;
-#ifdef _WIN32
-  ret = _mkdir (dirname.c_str ());
-#elif unix
-  ret = mkdir (dirname.c_str (), 0775);
-#elif __APPLE__
-  ret = mkdir (dirname.c_str (), 0775);
-#endif
-  (void) ret;
-}
-
 void
 dump_function_bir (const std::string &filename, BIR::Function &func,
 		   const std::string &name)
@@ -61,7 +47,7 @@ BorrowChecker::go (HIR::Crate &crate)
 
   if (enable_dump_bir)
     {
-      mkdir_wrapped ("bir_dump");
+      mkdir ("bir_dump", 0755);
       auto mappings = Analysis::Mappings::get ();
       bool ok
 	= mappings->get_crate_name (crate.get_mappings ().get_crate_num (),
diff --git a/gcc/rust/expand/rust-proc-macro.cc b/gcc/rust/expand/rust-proc-macro.cc
index 09680733e98..d658b4d10db 100644
--- a/gcc/rust/expand/rust-proc-macro.cc
+++ b/gcc/rust/expand/rust-proc-macro.cc
@@ -22,7 +22,10 @@
 #include "rust-token-converter.h"
 #include "rust-attributes.h"
 
-#ifndef _WIN32
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else
 #include <dlfcn.h>
 #endif
 
@@ -102,12 +105,16 @@ static_assert (
 
 } // namespace
 
-template <typename Symbol, typename Callback>
+template <typename Handle, typename Symbol, typename Callback>
 bool
-register_callback (void *handle, Symbol, std::string symbol_name,
+register_callback (Handle handle, Symbol, std::string symbol_name,
 		   Callback callback)
 {
+#ifdef _WIN32
+  FARPROC addr = GetProcAddress (handle, symbol_name.c_str ());
+#else
   void *addr = dlsym (handle, symbol_name.c_str ());
+#endif
   if (addr == nullptr)
     {
       rust_error_at (UNDEF_LOCATION,
@@ -129,7 +136,18 @@ register_callback (void *handle, Symbol, std::string symbol_name,
 const ProcMacro::ProcmacroArray *
 load_macros_array (std::string path)
 {
-#ifndef _WIN32
+#ifdef _WIN32
+  HMODULE handle = LoadLibraryA (path.c_str ());
+  // We're leaking the handle since we can't ever unload it
+  if (!handle)
+    {
+      char msg[300];
+      FormatMessageA (FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                      nullptr, GetLastError (), 0, msg, sizeof msg, nullptr);
+      rust_debug ("Error whilst opening procedural macro: %s", msg);
+      return nullptr;
+    }
+#else
   void *handle = dlopen (path.c_str (), RTLD_LAZY | RTLD_LOCAL);
   // We're leaking the handle since we can't ever unload it
   if (!handle)
@@ -137,6 +155,7 @@ load_macros_array (std::string path)
       rust_debug ("Error whilst opening procedural macro: %s", dlerror ());
       return nullptr;
     }
+#endif
 
   if (!REGISTER_CALLBACK (handle, __gccrs_proc_macro_ts_from_str_,
 			  tokenstream_from_string))
@@ -153,12 +172,12 @@ load_macros_array (std::string path)
   auto symbol_name = generate_proc_macro_decls_symbol (0 /* FIXME */);
 
   return *reinterpret_cast<const ProcMacro::ProcmacroArray **> (
-    dlsym (handle, symbol_name.c_str ()));
+#ifdef _WIN32
+    GetProcAddress (handle, symbol_name.c_str ())
 #else
-  rust_sorry_at (UNDEF_LOCATION,
-		 "Procedural macros are not yet supported on windows host");
-  rust_unreachable ();
+    dlsym (handle, symbol_name.c_str ())
 #endif
+    );
 }
 
 #undef REGISTER_CALLBACK
diff --git a/gcc/rust/parse/rust-parse.cc b/gcc/rust/parse/rust-parse.cc
index 504a409cc4d..634ad0bf0c8 100644
--- a/gcc/rust/parse/rust-parse.cc
+++ b/gcc/rust/parse/rust-parse.cc
@@ -89,7 +89,7 @@ extract_module_path (const AST::AttrVec &inner_attrs,
   // Source: rustc compiler
   // (https://github.com/rust-lang/rust/blob/9863bf51a52b8e61bcad312f81b5193d53099f9f/compiler/rustc_expand/src/module.rs#L174)
 #if defined(HAVE_DOS_BASED_FILE_SYSTEM)
-  path.replace ('/', '\\');
+  std::replace (path.begin (), path.end (), '/', '\\');
 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 
   return path;